81697387 has 2 divisors, whose sum is σ = 81697388. Its totient is φ = 81697386.

The previous prime is 81697381. The next prime is 81697409. The reversal of 81697387 is 78379618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81697387 - 2¹⁵ = 81664619 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81697387.

It is not a weakly prime, because it can be changed into another prime (81697381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40848693 + 40848694.

It is an arithmetic number, because the mean of its divisors is an integer number (40848694).

Almost surely, 2^81697387 is an apocalyptic number.

81697387 is a deficient number, since it is larger than the sum of its proper divisors (1).

81697387 is an equidigital number, since it uses as much as digits as its factorization.

81697387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 508032, while the sum is 49.

The square root of 81697387 is about 9038.6606861858. The cubic root of 81697387 is about 433.9130603033.

The spelling of 81697387 in words is "eighty-one million, six hundred ninety-seven thousand, three hundred eighty-seven".